High speed contact operating mechanisms have substantially reduced the amount of current to be interrupted upon the instant of contact separation. The reduced amount of current carried by the contacts during the instant of switching, in turn, has substantially reduced the magnitude of the arc that occurs when the contacts become separated. Previously known solid state current interruption devices arranged in parallel across the contacts transfer the current away from the contacts at the instant of contact operation and thereby allow the contacts to separate a sufficient distance, such that the arc that occurs upon separation of the contacts becomes extinguished. A supplemental series-connected switch is then opened to completely interrupt the current. So-called "virtually arcless" circuit interruption is accomplished by diverting most of the circuit current away from the contacts prior to actuating the contact operator for contact separation, such that insufficient current remains to sustain an arc of any significance. The diverted current first passes through a power transistor and then through a varistor wherein the current rapidly approaches zero.
One of the problems involved with such high speed current limiting circuit interruption is the need to ensure that the contacts do not become separated until after the current has been diverted. Some means of synchronization between the operation of the solid state current interrupter and the contact operator is required to ensure this function. One purpose of the instant invention is to provide a circuit arrangement wherein the diverted current, per se, is used to both turn on the solid state current interrupter and to activate the contact operator to separate the contacts immediately after the circuit current has been diverted.